Symposium : N
Control of light at the nanoscale: materials, techniques and applications
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| Active nanophotonics I : Mario Agio | ||
| 08:30 | Integrated plasmonic devices Authors : Anatoly V Zayats Affiliations : Department of Physics, King's College London, Strand, London, WC2R 2LS, United Kingdom Resume : Plasmonics deals with surface electromagnetic excitations in metallic structures and provides a great deal of flexibility in photonic integration since with surface plasmons the problem of light manipulation can be reduced from three to two dimensions. The electromagnetic field enhancement effects associated with surface plasmons and specific to them field confinement near metal interfaces result in the strong sensitivity of plasmonic mode to dielectric surroundings, thus facilitating all-optical and electronic control of their propagation. Many types of plasmonic nanostructures, such as waveguides, crystals and metamaterials can be designed to incorporate active material, such electro-optical, nonlinear-optical and gain materials. The choice of the waveguiding platform allows control over mode dispersion, mode confinement and propagation loss. In this talk we will overview plasmonic approaches for achieving subwavelength guiding and manipulation of optical signals. Generation, detection, amplification and modulation of plasmonic signals in the integrated circuitry will also be discussed.
This work has been supported by EPSRC (UK). | 13 1 |
| 09:00 | Characterization of thermo-optical 2x2 switch configurations made of dielectric loaded surface plasmon polariton waveguides for telecom routing architecture Authors : K. Hassan, J.-C. Weeber, L. Markey, A. Dereux; A. Pitilakis, O. Tsilipakos, and E.E. Kriezis Affiliations : Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 Université de Bourgogne, 9 avenue A. Savary, F-21078 Dijon, France; Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece Resume : We report on experimental characterization of Dielectric Loaded Surface Plasmon Polariton Waveguide (DLSPPW) thermo-optic switches structures for high data bit rate transfer. The development of active components made of DLSPPWs is a promising ways to integrate photonics components on-chip. DLSPPWs are comprised of a dielectric ridge (usually a polymer) with a typical cross-section of 0.5x0.5 µm² deposited onto a thin metal film. The fundamental mode travelling along these waveguides is a plasmonic quasi-TM polarized mode. Many passives components based of DLSPPW have been demonstrated and an efficient coupling of DLSPPW waveguides with SOI optical circuitry has been reported. Beyond passive components, dynamically controlled DLSPPW based devices are of practical interest. In this context, owing to the potentially large thermo-optical coefficient of the dielectric load, thermally activated DLSPPW devices have been proposed. In this work, we focus onto thermally controlled switches relying on either X-add-drop or Dual Mode Interference configurations. The performances of the switches are extracted from leakage radiation microscopy images. The experimental characterizations reveal extinction ratio larger than 5dB over bandwidth larger than 4.5nm. | 13 2 |
| 09:15 | Efficient thermo-optically controlled Mach-Zhender Interferometer using dielectric-loaded plasmonic waveguides Authors : Jacek Gosciniak 1,* Sergey I. Bozhevolnyi 1, Laurnet Markey 2, and Alain Dereux 2 Affiliations : 1. Institute of Technology and Innovation, University of Southern Denmark, Niels Bohrs Alle 1, DK-5230 Odense M, Denmark 2. Institut Carnot de Bourgogne, UMR 5209 CNRS-Universite de Bourgogne, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex, France Resume : Compact fiber-coupled DLSPPW-based MZI modulated by the external voltage base on the thermo-optic effect will be presented. Two sets of samples were fabricated and compared with PMMA and Cyclomer ridge and with the Cytop as a supporting material below gold electrodes showing significant improvement in the performance of such MZI compare to the previous studies where the magnesium fluoride was used and which is attributed to the lower thermal conductivity coefficient of the Cyclomer (0.12 W/mK) compare to MgF2 (11.6 W/mK). In this way, the heating efficiency of the ridge is increased and the total power efficiency for switching purpose is decreased. The experiments have shown 100% output modulation with Cyclomer-loaded MZI and 40 % modulation with PMMA-loaded structure what results from 3 times larger thermo-optics coefficient of Cyclomer than PMMA.
For the MZI with a Cyclomer ridge, a low switching power of 2.35 mW was obtained with a 10 - 90 % rise time of 120 µs and 90 – 10 % fall time of 32 µs. The switching time was reduced by over 350 times compared to a structure with PMMA ridge with the same design what should be attributed mainly to the thermal properties of Cyclomer and partially to the smaller high of the ridge. Presence of the Fabry-Perot cavity in the modulated arm of the Mach-Zehnder interferometer cause it works as a wavelength-selective component. | 13 3 |
| 09:30 | Single-Mode Laser Operation of CdSe/CdS Core/Shell Colloidal Quantum Rods on Silica Microspheres Authors : C. Grivas1, P. Andreakou1, P. Wang2, M. Ding2, G. Brambilla2, L. Manna3, and P. G. Lagoudakis1 Affiliations : 1 School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK; 2 Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK; 3 Istituto Italiano di Tecnologia (IIT) I-16163 Genoa, Italy Resume : Single-mode operation of fiber-coupled hybrid lasers based on colloidal CdSe/CdS core/shell nanorods in silica microspheres is reported. The spheres were pumped at a wavelength around 400 nm with a tunable frequency doubled Ti:sapphire amplifier, operating at 250 KHz and emitting 180-fs-short pulses with a linewidth of 5 nm. Pump pulses were evanescently coupled into the spheres with adiabatic tapers made of single-moded fibers at 405 nm. Laser signals were collected by either a fiber tip with a diameter of ~50 nm or, the same taper used for pumping. To optimize pump efficiencies, phase-matching of the propagation coefficients between the propagating mode in the taper and the fundamental whispering-gallery-mode (WGM) in the microsphere was established.
Single-WGM operation at ~628 nm, corresponding to the 1Sh-1Se(CdSe) transition of a microsphere with a 9.2 µm diameter was obtained by resonant pumping a fundamental WG pump mode at the equatorial ring of the sphere with │m│ = l, where m and l are the angular momentum and the azimuthal numbers, above an absorbed pump power threshold of 67.5 µW. Microspheres with larger diameters produced multimode laser emission. A maximum output power of 5.5 µW for 155 µW of absorbed power was measured, corresponding to a slope efficiency of 6.4%.
Wavelength tunability over a range of 2.1 nm (which corresponds to 30% of the FSR) was achieved for the lasing wavelength, by heating with 3.5-µm-pulses of 200 fs duration and 80 MHz repetition rate. | 13 4 |
| 09:45 | Self-Collimation, Steering and Negative Refraction of Surface Plasmon Beams Authors : Benedikt Stein, Eloïse Devaux, Cyriaque Genet, and Thomas W. Ebbesen Affiliations : ISIS, Université de Strasbourg & CNRS, 67000 Strasbourg, France Resume : Surface plasmon polaritons have raised renewed interest over the past decade for their potential in optical devices and circuits [1]. Inspired by the design principles of photonic band-gap materials [2,3], we have studied the propagation of surface plasmon beams through singly and doubly periodic metallic gratings.
Large beam steering effects are experimentally revealed by probing the isofrequency surfaces related to propagating Bloch waves inside the gratings. In particular, negative refraction is demonstrated close to the Bragg condition [4].
Molding the shape of isofrequency surface can also lead to flat band structures. Weakly diffracting self-collimating SP beams in such gratings will be presented, demonstrating an alternative route towards non-diffracting plasmon beams.
[1] Ebbesen, T.W.; Genet, C.; Bozhevolnyi, S. I. Physics Today, Vol. 61, No. 5. 2008, 44-50.
[2] Zengerle, R. Journal of Modern Optics 1987, 34, 1589
[3] Russell, P.S.J. Phys. Rev. A. 1986, 33, 3232
[4] B Stein, JY Laluet, E Devaux, C Genet, TW Ebbesen Phys. Rev. Lett. 105 266804 (2010) | 13 5 |
| 10:00 | Coffee break | |
| Active nanophotonics II : Anatoly Zayats | ||
| 10:30 | Optical real space imaging of gate-tuneable graphene plasmons Authors : Frank Koppens , Michela Badioli, Jianing Chen, Pablo Alonso, Suko Thongrattanasiri, Florian Huth, Johann Osmond,Marko Spasenović, Amaia Zurutuza, Alba Centeno, Amaia Pesquera , Nicolas Camara , Philippe Godignon ,Javier Garcia de Abajo, Rainer Hillenbrand Affiliations : ICFO, The insttute of photonics Sciences, Barcelona (Spain); NanoGune, San Sebastian (Spain); Graphenea, NanoGune (Spain); University of Tours; CNM-IMB (Barcelona); IQFR-CSIC, Madrid (Spain) Resume : Graphene has recently emerged as an intrinsically two-dimensional material with unique electrical and optical properties [1]. Graphene has zero band gap, electrically tunable electron/hole doping, high-mobility charge carriers with an effective mass of zero and - despite its thickness of a single atomic layer - it still absorbs significant (~2.3%) light in the visible and near infrared region. Because these unique characteristics are all present in one material, it has great potential for opto-electronic applications, such as ultrafast photo-detection and optical switches.
Interestingly, graphene is also a promising host for optical plasmons: surface waves coupled to charge carrier excitations of the conducting sheet [2]. In this talk, I will discuss our recent experimental observations of spatially resolved graphene surface plasmons, obtained by scattering near-field microscopy. Interference fringes of propagating plamsons have been observed, from which we extract the plasmon dispersion. The plasmonic optical field confinement is remarkably strong, with a wavelength more than a factor of 100 below the excitation wavelength. This extremely strong optical field confinement can explained by the the unique conductance properties of graphene and its two-dimensional character.
The true potential of graphene plasmonics is revealed by our implementation of a "plasmon-transistor". By tuning the carrier density, we can control the plasmon wavelength over a wide range. At sufficiently low carrier densities, plasmon propagation is fully quenched, providing us with a gate-controlled plasmon-switch.
This research will reveal the far-reaching potential of a single sheet of carbon atoms as a host for guiding and manipulating light and electrons at the nanoscale, with prospects for strongly enhanced light-matter interactions [3,4], ultra-thin metamaterials [5], and novel active opto-electronic functionalities and devices [6].
[1] K.S. Novoselov et al., Nature 438, 197 (2005)
[2] M. Jablan et al. Phys. Rev. B 80, 245435 (2009)
[3] F.H.L. Koppens, D.E. Chang, J. Garcia de Abajo, Nanoletters 11, 3370 (2011)
[4] Y.Y. Nikitin et al, Arxiv 1104.3558 (2011)
[5] A. Vakil, N. Engheta, Science 332, 1291–1294 (2011)
[6] Thongrattanasiri,Koppens, Garcia de Abajo, PRL (2012) | 14 1 |
| 11:00 | Active Loss Compensation in Confined Surface Plasmon Polariton Waveguides Authors : S. Kena-Cohen, P. Stavrinou, D.D.C.Bradley, S. A. Maier Affiliations : Imperial College London Resume : Propagation losses are well known to be a major obstacle to the large scale integration of surface plasmon polariton (SPP)-based optical components. There have, however, been recent demonstrations of surface plasmon amplification in symmetric waveguides supporting so-called long range surface plasmon polaritons (LRSPPs). Losses in such structures can be minimised, but the degree of confinement remains comparable to that achievable using conventional dielectric waveguides. To our knowledge, the best loss compensation achieved in confined SPP waveguides is on the order of 30%. Net gain remains, as of yet, elusive.
Here, we present theoretical simulations and experimental results for a hybrid SPP waveguide capable of achieving net gain. By controlling the spatial pump distribution and using a thin metal layer, net gain is predicted to occur for pump powers < 100 kW/cm2. To realise the proposed structure, a new fabrication strategy is demonstrated which allows the use of ultrathin gold films, combined with multiple electron-beam lithography overlays, without the need for a sticking layer. Initial loss-compensation results from waveguides using a 125 nm-thick Alq3:DCM active layer will be presented. | 14 2 |
| 11:15 | Resonant extinction in free-standing arrays of non-resonant nanorods Authors : Petru Ghenuche(1,2), Gregory Vincent(2), Marine Laroche(3), Nathalie Bardou(1), Riad Haidar(2), Jean-Luc Pelouard(1), Stephane Collin(1) Affiliations : 1. Laboratoire de Photonique et Nanostructures (LPN-CNRS), Route de Nozay, 91460 Marcoussis, France; 2. Onera - The French Aerospace Lab, Chemin de la Huniere, 91761 Palaiseau, France; 3. Laboratoire Charles Fabry, Institut d’Optique, CNRS, Universite Paris-Sud, Campus Polytechnique, RD 128, 91127 Palaiseau cedex, France Resume : We experimentally demonstrate that nearly 100 % of incident photons can interact with a monolayer of sparse and non-resonant
scatterers, periodically arranged in a symmetrical environment. This nearly-perfect optical extinction through free-standing transparent nanorods originates from a multiple-scattering process.
Freestanding Si3N4 membranes made of subwavelength square rods (width between λ/5 − λ/10) were fabricated on a Si substrate
and drilled by dry etching. High-resolution dispersion diagrams have been measured for the absolute transmission and reflection for several arrays with one-dimensional and two-dimensional patterns.
Remarkably for a transparent material with a fill factor of only 15%, up to 96% extinction, independent of polarization, is found. In addition, when lossy material is used to fabricate the rods, an absorption enhancement factor of 25 is found, an indication of the electric field enhancement that occurs in the vicinity of the rods.
A key advantage of such dielectric gratings is the ease of tuning the resonance parameters by changing the geometrical parameters (period and radius of the rod, respectively) without being restricted to the range of frequencies of plasmons. The employment of these geometrical resonances in dielectric systems may provide new opportunities for applications like optomechanics, stop-band/band-pass filters and selective mirrors, and also for applications where fluorescence quenching must be avoided. | 14 3 |
| 11:30 | Collective plasmon response in arrays of metallic nanoparticles Authors : A.Slablab1), P.E.Coulon1), S.Perruchas2), T.Gacoin2), I.Monnet3), J.Cardin3), A. Fafin3), C.Dufour3), A.Losquin4), M.Kociak4), D.Mailly5) and G.Rizza1), Affiliations : 1) LSI, Ecole Polytechnique, 91128 Palaiseau Cedex, France, 2) LPMC, Ecole Polytechnique, 91128 Palaiseau Cedex, France, 3) CIMAP, 14070 Caen Cedex 5, France, 4) LPS, Bâtiment 510, Université Paris Sud XI, F 91405 Orsay, France, 5) LPN, CNRS, Marcoussis, France. Resume : Plasmonics aims to exploit the unique optical properties of metallic nanostructures to enable the routing and the active manipulation of light at the nanoscale. However, the broad plasmon resonance of individual NPs limits the potential applications. A promising way to improve the quality of the LSPRs in to create Fano resonaces [1-6]. When light is incident on an array of NPs, it is scattered by different elements in the structure. The presence of order in the system enables the appearance of coherent effects among the various scattered waves. These new modes are called lattice surface modes (LSMs) and are characterized by very narrow symmetric and asymmetric (Fano) peaks. The LSMs modes represent a new decay channel for emitters and offer new routes for the design of nano-structured surfaces that enable a control of the spontaneous emission. Fano resonances possess an inherent sensitivity to changes in geometry or in the local environment: small perturbations can induce dramatic shifts in the resonance or line shape and exceptionally large field enhancements. These properties render Fano resonant media particularly attractive for a range of applications spanning from plasmonic photovoltaics, to bio-sensing, SERS and SEIRA spectroscopies.
The objective of this study is to investigate how both the pattern of the array. | 14 4 |
| 11:45 | Lunch break | |
| Plasmonics in other fields : Chris Geddes | ||
| 13:15 | Nano-opto-mechanical phenomena in plasmonic metamaterials Authors : N.I.Zheludev Affiliations : Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, SO17 1BJ, UK Resume : At the nanoscale electrostatic and electromagnetic forces become sufficient to drive new intriguing and useful optical phenomena. | 15 1 |
| 13:45 | Engineered plasmonic nanoslit-cavity for optical trapping and molecular sensing Authors : Chang Chen1,2, Mathieu L. Juan3, Yi Li1,4, Liesbet Lagae1,2, Romain Quidant3,5, Pol Van Dorpe1,4, Affiliations : 1 imec, kapeldreef 75, 3001 Leuven, Belgium; 2 Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium; 3 ICFO-Institut de Ciences Fotoniques, Mediterranean Technology Park, 08860 Castelldefels, Spain; 4 Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, 3001 Leuven, Belgium; 5 ICREA-Institució Catalana de Recerca i Estudis Avançts, Barcelona, 0810, Spain; Resume : Surface plasmon polaritons (SPPs) have been widely used for concentrating light down to the sub-wavelength level or even to the nanometer scale.[1] Many dedicated micro/nano-structures have already been proved as excellent plasmonic waveguides, lens, mirrors, filters and sensors, showing the huge feasibility in a broad range of applications. In this paper, we would like to introduce our novel plasmonic nanoslit-cavity device and its application for enhanced optical trapping at a low power and (bio)chemical sensing for the trace analysis.
In a freestanding membrane we fabricated a tapered rectangular nanopore and covered it with gold, resulting in a lateral metal-air-metal cavity.[2] The excitation of SPPs in the cavity is facilitated by engineering the length of the taper sidewall and is resonant at specific wavelengths due to a Fabry-Pérot resonance between the end sides of the nanoslit-cavity.[3] Benefiting of the highly compressed SPPs inside the nanoslit, the intensity of the optical field near the middle of the edge of the slit is strongly enhanced, with enhancement factors of 1000~10000 at resonance. Moreover, the light transmitted through the subwavelength slit is also strongly improved, and the enhanced regions (hot spots) are only highly concentrated inside the slit.[4] These critical properties suggest that, this kind of devices have promising applications in trapping and spectroscopy of nanoscale objects and molecules.
As is well-known, gentle manipulation of micrometer-sized dielectric objects with optical forces has found many applications in both life and physical sciences. To further extend optical trapping towards the true nanometer scale, plasmonic trapping becomes an important tool, especially combing a strategy called the self-induced back action (SIBA) trapping.[5] In this strategy, the trapped object plays a direct and active role in the trapping process. As a part of the SIBA strategy, when the object is trapped, it will influence the local field distribution and induce a red-shift of the resonance. Since the plasmonic resonance is reflected in the spectrum of the transmitted light, the induced red-shift can lead to a significant signal variation in the transmission, proving an effective and simple method for studying the trapping process. In this work, we combined the SIBA with the latest advances in nanoscale plasmon engineering.[6] The designed resonant trap, formed by a rectangular plasmonic nanopore (a short nanoslit), is successfully tested on 22 nm polystyrene beads under a 1064 nm laser with a power at 2.5 mW, showing both single-bead and double-bead trapping events. The mechanism responsible for the higher stability of the double-bead trapping is discussed, in light of the statistical analysis of the experimental data and numerical calculations.
Beyond trapping the nano-objects, the nanoslit-cavity device also shows a high accuracy and sensitivity on identifying analytes through surface enhanced Raman spectroscopy (SERS). SERS is a widely accepted analytical method providing molecular information with the sensitivity at the single molecule level. Here, we combine the SERS with the conventional nanopore fluidics technology. In nanopore fluidics, the nanopore is used to mechanically confine single particles or molecules.[7] With the assistance of this method, translocations of analytes through the hot spots of the nanoslit-cavity will be simultaneously recognized by SERS.[8] Until now, the identification on different self-assembled monolayers, small organic molecules such as nucleotides, DNA oligos and lambda-DNA have been investigated.
In a short conclusion, the engineered plasmonic nanoslit-cavity devices have been successfully applied in the optical trapping of 22 nm nanobeads and SERS for molecular identification. Although it is not yet clear whether small molecules like nucleotides can be indeed trapped, our nanoslit-cavity may become a useful platform for immobilizing those larger biomolecules such as viruses, proteins, or even DNA strands.
Acknowledgements
C. C. and P. V. D. gratefully acknowledge financial support from the FWO (Flanders).
References
[1.] A. S. Maier, Plasmonics: Fundamentals and Applications, (Springer, New York), 2007.
[2.] C. Chen, J. A. Hutchison, P. Van Dorpe, R. Kox, I. De Vlaminck, H. Uji-i, J. Hofkens, L. Lagae, G. Maes, G. Borghs, Small, 2009, 5, 2876.
[3.] C. Chen, L. Lagae, G. Maes, G. Borghs, P. Van Dorpe, Phys. Status Solidi-R., 2010, 4, 247.
[4.] C. Chen, P. Van Dorpe, J. A. Hutchison, F. Clemente, R. Kox, H. Uji-i, J. Hofkens, L. Lagae, G. Maes, G. Borghs, Angew. Chem. Int. Ed., 2009, 48, 9932.
[5.] M. L. Juan, R. Gordon, Y. J. Pang, F. Eftekhari, R. Quidant, Nat. Phys., 2009, 5, 915.
[6.] C. Chen, M. L. Juan, L. Yi, G. Maes, G. Borghs, P. Van Dorpe, R. Quidant, Nano Lett., 2011, ASAP.
[7.] C. Dekker, Nat. Nanotechnol., 2007, 2, 209.
[8.] C. Chen, R. Kox, F. Clemente, L. Lagae, G. Maes, G. Borghs, P. Van Dorpe, XXII International Conference on Raman Spectroscopy – ICORS, Boston, 2010. | 15 2 |
| 14:00 | Plasmonic coherent drive of an optical trap Authors : A. Cuche, O. Mahboub, E. Devaux, C. Genet, and T.W. Ebbesen Affiliations : ISIS, University of Strasbourg and CNRS, 8 all?Gaspard Monge, 67000 Strasbourg, France Resume : Since the first demonstration of optical trapping with localized surface plasmons (LSP) on metallic pads in 2007 [1], the ability to manipulate small objects using the mechanical properties of propagating surface plasmons (SP) has become a topic of intense research. In this context of plasmonic opto-mechanics, we will demonstrate in this presentation that optical trapping can be driven by delocalized SPs resonantly excited within a standing wave trap (SWT) [2]. Dynamical modifications of the trap are shown to be determined by the near-field symmetry of the SP modes excited on an extended structure, with negligible thermal effect. With low trapping powers and polarization control, remarkable stiffness enhancements are recorded, the larger the smaller the particle. The results can be simply modeled accounting for a coherent interaction between the SP field, with a symmetric or an antisymetric profile, and the Gaussian standing wave of the trap. Here we used a very simple nanostructure but a rich variety of dynamical effects are expected when designing more complex ones. Moreover the optical simplicity of our setup, combined with the low trapping powers, makes it truly compatible and easily integratable into optofluidics systems. This work opens appealing perspectives for trapping small objects (metallic particles), and possibly quantum objects in microfluidic environment.
[1] M. Righini et al., Nature Phys. 3, 477 (2007)
[2] A. Cuche et al., Phys. Rev. Lett. Accepted (2011) | 15 3 |
| 14:15 | Ultra-compact grating-coupled plasmonic sensing for high-resolution analysis with polarization modulation Authors : G. Ruffato(1,2,3), A. Sonato(1,2), G. Zacco(1,2,3), E. Pasqualotto(4), D. Silvestri(5), M. Morpurgo(5), A. De Toni(4), F. Romanato(1,2,3) Affiliations : (1) University of Padova, Department of Physics and Astronomy, via Marzolo 8, 35131 Padova, Italy; (2) Laboratory for Nanofabrication of Nanodevices, LaNN – Venetonanotech, Corso Stati Uniti 4, 35127 Padova, Italy; (3) CNR-INFM TASC IOM National Laboratory, Area Science Park, S.S. 14 km 163.5, 34012 Basovizza, Trieste, Italy; (4) University of Padova, Department of Information Engineering, via Gradenigo 6, 35131 Padova, Italy; (5) University of Padova, Department of Pharmaceutical Sciences, Via Marzolo 5, 35131 Padova, Italy Resume : A Grating-Coupled Surface Plasmon Resonance (GCSPR) technique based on polarization modulation in the conical mounting is presented. A metallic grating is azimuthally rotated in order to support a double excitation of surface plasmon polaritons that can be exploited in order to provide a sensitivity enhancement [1,2]. In correspondence of the resonance polar angle, a polarization scan of incident light is performed and reflectivity data are collected before and after surface functionalization. Output signal exhibits a harmonic dependence on polarization and the phase term is used as a parameter for sensing. Since the configuration is kept fixed during the measurement and the only degree of freedom is represented by polarization, the mechanical complexity of the analysis system is significantly reduced. Moreover the setup assures great performance and benefits in sensitivity and resolution. Thus plasmonics underlying metallic gratings in the conical mounting, offers the possibility to design extremely compact, fast and cheap high-resolution plasmonic devices for sensing purposes [3]. The adsorption mechanism of a thiolated poly(ethyleneoxide) (mPEO-Cys, Mw 5 KDa) monolayer on the grating was studied and the sensing platform was also verified in a model biorecognition assay using the avidin/biotin system.
[1] F. Romanato et. al.,Opt.Express17,12145-12154 (2009).
[2] Romanato et al.,Appl.Phys.Lett.96, 111103 (2010).
[3] G. Ruffato, F. Romanato,submitted to Optics letters (2012) | 15 4 |
| 14:30 | Confinement effect of the Localized Surface Plasmons on the coupling of gold nanolithographied structures: Application to Surface Enhanced Raman Scattering Authors : N. Guillot1, C. D’Andrea2, A. Toma3, P. Albella4, R. P. Zaccaria3, E. Di Fabrizio3, J. Aizpurua4, P. G. Gucciardi2 and M. Lamy de la Chapelle1* Affiliations : 1 Université Paris XIII, Laboratoire CSPBAT (FRE 3043), UFR SMBH, équipe LBPS, 93017 Bobigny, France 2 IPCF-Messina, V.le F. Stagno D'Alcontres, 37, c.da Papardo, 98158 Messina, Italy 3 Istituto Italiano di Tecnologia (IIT). Via Morego, 30 16163 Genova, Italy. 4 Centro de Fisica de Materiales, CSIC – UPV/EHU, Paseo Manuel de Lardizabal 4, Donostia-San Sebastian 20018, Spain ; Donostia International Physics Center DIPC, CIC NanoGUNE Consolider, P. Mikeletegi 56, 20009 Donostia- San Sebastian, Spain Resume : In the field of molecular detection by Surface Enhanced Raman Scattering (SERS), many efforts have been made to develop optimized substrates providing the highest enhancement of SERS and enabling the observation of the lowest concentration of analytes [1,2]. These efforts have been mainly focus on the electromagnetic process. In the purpose of creating intense local electromagnetic fields, sharp and elongated nanoparticles like nanorods or nanowires are known to be more efficient than spherical ones because they confine the LSP at their extremities and give rise to the tip effect [3]. However, it is assumed that the best enhancement should be reached for coupled nanoparticles. Indeed, when the interparticle distance is of few nanometers, a high field is observed in the gap and is known as “hot spot”.
In this work, we present for the first time the influence of the LSPs confinement on the coupling of the electromagnetic fields provided by elongated gold nanostructures oriented tip-to-tip and the consequence on the SERS efficiency. To investigate the coupling effect between gold nanorods in dimer configuration, some samples with nanolithographied arrays of dimers have been fabricated on CaF2 substrates. The distance between every dimer is kept constant and set to 200 nm to avoid near field coupling effects between the dimers whereas the separation between each monomer in the long axis direction is reduced from 200 nm (non coupled case) to 10 nm.
In conclusion, we report that more elongated nanostructures obtain a smaller coupling decay length due to a higher LSP confinement and means that such structures must be much closer to couple as efficiently as smaller equivalent structures. The influence of the LSP confinement on the Raman intensity has been then discussed by showing that long enough coupling decay length lead to an exponential increase of the Raman intensity when decreasing the interparticle separation. We also notice the influence of the excitation wavelength on the coupling decay length and we observe that lower excitation wavelengths lead to higher LSP confinement and, as a consequence, decrease significantly the Raman intensity.
Acknowledgements, The authors want to acknowledge the Nanoantenna collaborative European project (HEALTH-F5-2009-241818) for financial support.
REFERENCES
1. Nie, S. and Emory, S. R., Science, Vol. 275, 1102, 1997.
2. Kneipp, K., Wang, Y., Kneipp, H., Perelman, L.T., Itzkan, I., Dasari, R.R. and Feld, M.S., Phys. Rev. Lett, Vol. 78, 1667, 1997.
3. Wokaun, A.W., in: Ehrenreich, H., Seitz, F., Turnbull, D. (Eds.), Solid State Phys., vol. 38, Academic Press, New York, p.223, 1984. | 15 5 |
| 14:45 | Coffee break | |
| Computational and theory : Nathalie de Leon | ||
| 15:15 | Light scattering under nanofocusing: Towards coherent nanoscopies Authors : (1) Ahmad Mohammadi, (2) Mario Agio Affiliations : (1) Department of Physics, Persian Gulf University, 75196 Bushehr, Iran; (2) Laboratory of Physical Chemistry, ETH Zurich, 8093 Zurich, Switzerland Resume : Optical nanoscopy is recognized as a powerful tool for investigating physico-chemical as well as biological processes in nanomaterials, whereby subwavelength spatial resolution is combined with a variety of spectroscopic techniques. The past decades have witnessed the development of several attempts in this regard, which have however suffered from the mismatch between light and nanoscale matter.
The dramatic advances of nanotechnology experienced in recent years have enabled us to fabricate optical nanostructures that greatly improve the conversion of localized electromagnetic energy into radiation and vice versa. In this context, it has been found that a truncated metal nanocone may focus light into nanoscale dimensions with minimal suffering from absorption losses and modify the radiation pattern of a light emitter placed near its tip.
Our aim is to combine coherent spectroscopy with nanofocusing to explore how this approach may expand the detection limits of nanoscale objects, with particular attention on the competition between the enhancement of light-matter interaction, coherent detection as well as damping and dephasing processes. We furthermore highlight the unique features of scattering under nanofocusing and derive expressions for the visibility and the phase shift caused by a polarizable object. At last we discuss how these concepts may be extended to ultrafast and nonlinear techniques, coherent control and multidimensional correlation spectroscopies. | 16 1 |
| 15:45 | Polariton Dynamics in Light-Molecule Strong Coupling Authors : Tal Schwartz, James A. Hutchison, Jérémie Léonard, Cyriaque Genet, Stefan Haacke, Thomas W. Ebbesen Affiliations : ISIS, Université de Strasbourg and CNRS (UMR 7006), 8 allée Gaspard Monge, 67000, Strasbourg, France; ISIS, Université de Strasbourg and CNRS (UMR 7006), 8 allée Gaspard Monge, 67000, Strasbourg, France; IPCMS, Department of Ultrafast Optics and Nanophotonics, UMR 7504 Université de Strasbourg - CNRS, 67034 Strasbourg, France; ISIS, Université de Strasbourg and CNRS (UMR 7006), 8 allée Gaspard Monge, 67000, Strasbourg, France; IPCMS, Department of Ultrafast Optics and Nanophotonics, UMR 7504 Université de Strasbourg - CNRS, 67034 Strasbourg, France; ISIS, Université de Strasbourg and CNRS (UMR 7006), 8 allée Gaspard Monge, 67000, Strasbourg, France Resume : Strong coupling of light and molecules is currently a subject of extensive study, and in the recent year it was demonstrated in various configurations, ranging from organic microcavities to plasmonic geometries such as metallic hole-arrays and nanoparticles. Such systems are highly attractive for fast switching, generation of coherent light (polariton lasing) and wavelength conversion applications and manifest a convenient tool to study quantum effects at room temperature. Here we present our experimental study of the dynamics of such coupled systems and the properties of the light-matter hybrid states, using both steady state and pump-probe spectroscopic methods. We find that the organic microcavity exhibits an ultrafast optical response (<100fs), much shorter than the natural response time of the bare organic dye. Moreover, using fluorescence measurements we find that the hybrid polariton states can exchange energy with a pool of incoherent, non-coupled states that are present in the organic systems. These results raise many interesting questions regarding the dynamics of strong coupling in organic system – does the system reach thermal equilibrium? How does the properties of the polariton states change as a result of the high complexity of the organic active material? Our experiments aim at building a clear picture of these underlying physical processes, which will allow the future development of strongly coupled organic-based photonic devices. | 16 2 |
| 16:00 | Efficient control of spontaneous light emission by elastic waves Authors : E. Almpanis, G. Gantzounis, I.E. Psarobas, N. Papanikolaou, C. Tserkezis, N. Stefanou, B. Djafari-Rouhani, Y. Pennec, V. Laude, A. Martinez Affiliations : Institute of Microelectronics, NCSR “Demokritos”, Ag. Paraskevi, GR-153 10 Athens, Greece ; Institute of Microelectronics, NCSR “Demokritos”, Ag. Paraskevi, GR-153 10 Athens, Greece ; Institute of Microelectronics, NCSR “Demokritos”, Ag. Paraskevi, GR-153 10 Athens, Greece ; Institute of Microelectronics, NCSR “Demokritos”, Ag. Paraskevi, GR-153 10 Athens, Greece ; Section of Solid State Physics, University of Athens, Panepistimioupolis, GR-157 84 Athens, Greece ; Section of Solid State Physics, University of Athens, Panepistimioupolis, GR-157 84 Athens, Greece ; IEMN, Universite de Lille 1, 59655 Villeneuve d' Ascq, France ; IEMN, Universite de Lille 1, 59655 Villeneuve d' Ascq, France ; Institut FEMTO-ST, Universite de Franche-Comte, CNRS, Besancon, France ; Nanophotonics Technology Center, Universidad Politecnica de Valencia, Valencia, Spain Resume : The efficiency of light emitters can be enhanced in a photonic structure that supports localized light modes. More recently, strong acousto-optic interaction was predicted in appropriately designed microcavities that simultaneously localize light and elastic waves (phonons). For cavities of submicron dimensions, visible to near infrared light could be squeezed in a small volume, resonantly vibrating at GHz frequencies due to the elastic wave. When both elastic and optical fields are on resonance, multiphonon exchange mechanisms become significant, and dynamical optical frequency shift is enhanced. We investigate the influence of dual photonic-phononic resonant excitation on the spontaneous light emission of active centers. We consider a Si/SiO2 periodic multilayer structure, which operates as a Bragg mirror for both photons and phonons, with a defect layer (cavity) in the middle. Our calculation is based on the classical approach for light emission, and we solve the problem of an oscillating point dipole inside the multilayer structure using multiple-scattering Green's function techniques. The influence of the elastic wave is taken into account in a quasistatic picture, by considering both the bulk acousto-optic effect and the movement of the interfaces. Our results indicate that, through an elastic wave, it is possible to achieve strongly modulated light emission that escapes the multilayer slab and couples to traveling waves in the host medium. | 16 3 |
| 16:15 | Plasmonic Weak Measurements of Light Chirality Authors : Y. Gorodetski, S. Benedikt, C. Genet, T. W. Ebbesen; K. Y. Bliokh; N. Shitrit, V. Kleiner, and E. Hasman Affiliations : ISIS, Université de Strasbourg and CNRS, 8 allée Gaspard Monge, 67000 Strasbourg, France; A. Usikov Institute of Radiophysics and Electronics, NASU, Kharkov 61085, Ukraine; Micro and Nanooptics Laboratory, Faculty of Mechanical Engineering, and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel Resume : Polarization-dependent transverse shifts of spatially-confined optical beams - the spin Hall effect (SHE) of light, has become a topic of an intensive research. The SHE manifests itself in the opposite trajectory displacements of right-hand and left-hand circularly polarized beams reflected or refracted by a plane interface. Here, we demonstrate the surface-plasmon (SP) counterpart of SHE as a natural weak-measurement tool, owing to the fixed linear polarization of the surface mode, and probe the “weak value” of the light spin (polarization helicity). The subwavelength nature of the SHE makes it highly relevant for near-field optics, high-numerical-aperture microscopy, and, particularly, plasmonics. | 16 4 |
| 16:30 | Purcell factor for point-like dipolar emitter coupling 2D-plasmonic waveguides Authors : G. Colas des Francs, J. Barthes, A. Bouhelier, A. Dereux Affiliations : ICB, CNRS/Univ. Bourgogne Faculty Sciences Mirande 9, av. Savary - BP 47870 - 21078 Dijon Resume : We theoretically investigate spontaneous emission of a quantum (3D) dipolar emitter located near a (2D) plasmonic waveguide of arbitrary form. The channels into which emitter couples (plasmon, scattering, electron-hole pairs creation) are well identified. We achieve a closed form expression for the coupling rate into the guided SPP, extending the expression of the Purcell factor to plasmonic waveguide configuration [1]. We also investigate the radiative and non radiative channels. In particular, the contribution of the SPP mode to the non radiative rate, difficult to estimate otherwise, is clearly established. Our method relies on the numerical evaluation of the available relaxation channels at the emitter location [2]. It treats equivalently bound and leaky waveguides of arbitrary cross-section, possibly on a substrate. Finally, we apply this formalism to the description of integrated plasmonic amplifiers, that consists of a gain medium juxtaposed to a plasmonic waveguide [3]. Indeed, strong emission quenching for excited emitters in close proximity to the metal severely degrades the gain medium specifications [4] so that the competition between stimulated emission of SPP and quenching has to be carefully described [5].
References
1 Barthes et al., "Purcell factor for point-like dipolar emitter coupling to 2D-plasmonic waveguides", Phys. Rev. B (2011).
2 Colas des Francs et al., "Integrated plasmonic waveguides: mode solver based on density of states formulation", Phys. Rev. B 80 115419 (2009).
3 Grandidier et al., "Gain-Assisted Propagation in a Plasmonic Waveguide at Telecom Wavelength", Nano Lett. 9, 2935 (2009).
[4] de Leon, Berini,"Theory of SPP amplification in planar structures incorporating gain media", Phys. Rev. B 78, 161401 (2008).
[5] Colas des Francs et al, "Optical gain, spontaneous and stimulated emission of surface plasmon polaritons in confined plasmonic waveguide", Opt. Exp. 18, 16327 (2010). | 16 5 |
| 16:45 | Stationary and ultrafast transient optical responses of gold nanoparticles in a one-dimensional photonic crystal cavity Authors : Xiaoli Wang,(1), Roberta Morea,(2), Jose Gonzalo (2), Bruno Palpant(1) Affiliations : (1) Ecole Centrale Paris, Laboratoire de Photonique Quantique et Moléculaire, UMR 8537 – CNRS, Ecole Normale Supérieure du Cachan, Grande Voie des Vignes, 92295 CHÂTENAY-MALABRY cedex, France. (2) Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid, Spain. Resume : Metal-dielectric nanocomposites have attracted much attention as promising optical materials based on the surface plasmon resonance. Their optical properties can be modified on an ultrafast time scale by a series of energy conversion and exchanges processes following light pulse absorption. By playing together with these nanoscale photo-induced modifications and the processing of the composite medium in wavelength-scale structured devices, one may conceive optically controlled photonic functions. In this work, we use gold nanoparticles in the defect layer of a photonic-crystal based electromagnetic cavity. Both the stationary and ultrafast transient optical responses are investigated. We first show how the linear transmission varies with the concentration of gold nanoparticles and the angle of incidence of light. Then the ultrafast transient modification of the device transmittance is calculated in the very short time scale by solving Boltzmann equation for the electron distribution in the athermal regime together with the Rosei model for the metal energy band structure and Lindhard’s theory of the dielectric function. The transmission spectra are deduced from the transfer matrix method. We show that, under certain condition, the transient response of the nanocomposite medium can be enhanced by interference effects in the cavity. Finally, pump-probe spectroscopy experiments validate these simulations on a multilayer device elaborated by Pulsed Laser Deposition. | 16 6 |
| 17:00 | 2D metallic photonic quasicrystals Authors : Christina Bauer, Georg Kobiela, Harald Giessen Affiliations : 4th Physics Institute, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany Resume : Simulating the optical properties of 2D photonic quasicrystals [1] is often not possible due to their lack of periodicity. Therefore, a simulation model is required which is independent of the structural arrangement.
In this contribution we present a simulation model for a quasicrystalline arrangement of metallic nanodisks on top of a waveguide slab [2]. The incident linear polarization can excite waveguide modes. The propagation directions of the waveguide modes for normal light incidence are given by vectors pointing to the individual 2D Fourier peaks of the structure. For angular light incidence the kxy-component of the incident k-vector has to be added. In each propagation direction a TE as well as a TM wave can propagate in the waveguide. Therefore, the incident polarization Ea has to be split into a TE as well as a TM component. Additionally, particle plasmons can be excited in the metallic nanodisk. These particle plasmons can be considered as sources of independent, rotated material polarizations which can also excite waveguide modes. The spectra can then be calculated by using a Fano model [3] that takes the contributions above into account.
A quasicrystalline sample was measured for different incident polarizations as well as for varying incident angles. Our model shows excellent agreement with our simulations.
1 T. Matsui et al., Nature 446, 517 (2007).
2 A. Christ et al., Phys. Rev. Lett. 91, 183901 (2003).
3 A. Christ et al., Phys. Rev. B 76, 201405(R) (2007). | 16 8 |
| Poster session II : TBA | ||
| 17:45 | observation of strong quantum-confined Stark effect in individual localization centers within InGaN quantum-well based light emitting diodes Authors : Suman De, Subhabrata Dhar, Arindam Chowdhury Affiliations : Department of Chemistry, Indian Institute of technology Bombay; Department of Physics, Indian Institute of technology Bombay; Department of Chemistry, Indian Institute of technology Bombay; Resume : Using spectrally resolved photoluminescence imaging in a high throughput manner, we have demonstrated the extent of quantum confined stark effect (QCSE) in spontaneously formed individual emission centers within InGaN quantum well based light emitting diode. Understanding the effect of QCSE on optoelectronic behaviors of these highly localized emission enters is particularly important due to the fact that composition and morphology induced potential fluctuation in active layer is known to enhance the photoemission efficiencies by suppressing in-plane migration of carriers to non-radiative centers. The extent of the QCSE within these randomly dispersed individual radiative traps is extremely diverse, magnitude of which is dependent on carrier localization mechanisms. A self consistent Schrödinger-Poisson equation is solved to estimate the internal electrostatic field within these nano-structures, which suggest that the extent of this local intrinsic polarization field not only depends on morphology and composition of nanoscale domains, but also their dimension and strain relaxation therein. Moreover, screening of this electric field by photogenerated carriers leads to a shift in transition energies of up to ~400 meV, significantly higher than those observed for nitride based QW heterostructures. | 17 1 |
| 17:45 | Temperature dependent photoluminescence property of CdSe quantum dots and influence of shell injection temperature in CdSe/ZnS/CdSe quantum dot quantum wells Authors : Eun Yee Ko1,2, Ju-Won Jeon2, In Hwan Lee2, and Joo In Lee1,* Affiliations : 1 Nano imaging technology center, Korea Research Institute of Standards and Science, Daejeon, Korea 2 School of Advanced Materials Engineering and Research Center of Advanced Materials Development, Chonbuk National University, Jeonju, Korea Resume : This paper reports the temperature dependent photoluminescence (TDPL) property of the colloidal CdSe quantum dots (QDs) and the influence of the shell injection temperature on photoluminescence (PL) peak position of CdSe/ZnS/CdSe quantum dot quantum wells (QDQWs). The TDPL results on the CdSe QDs which were emitted at the wavelength of 488 nm using the Ar+ laser. The temperature range was from 15 K to 290 K. With the increase the temperature the PL peak position of the CdSe QDs shifted toward the lower energy to 35 meV. It is noticeably smaller than bulk CdSe (~ 100 meV). This property can give an advantage for an application to various devices. Two quantum systems as CdSe/ZnS/CdSe quantum dot quantum wells (QDQWs) have two different PL peak positions. The structural and optical properties of the outer shell (quantum well) is affected by an alteration of a shell injection condition. Photoluminescence (PL) results of CdSe/ZnS/CdSe QDQWs with two different shell injection temperatures which are 200 oC and 240 oC, respectively. The PL peak position of the QDQWs with the shell injection temperature of 240 oC shifted toward the lower energy compared to that of the QDQWs with the shell injection temperature of 200 oC. This result indicates the PL peak position of outer shell could be controlled by the shell injection temperature. | 17 2 |
| 17:45 | Theoretical studies of the physical properties of CdTe/CdZnTe for detection of radiations Authors : Asma Saim, A.Tebboune Affiliations : A.H.Belbachir Resume : Our research topic is ‘’The study of the properties of CdTe/ZnTe/CdZnTe for the detection of the radiations’’. This theoretical study which we went, fact the object of improving the performances of the detector with semiconductor. For our calculation we chose to work with the software Mindlab (MStudio version 5) which is based on the theory of the functional of density DFT with the approximation LMTO and LDA. With our software we will extract all information for the structural properties (crystalline), electronics, optics and plastics for CdTe with the four bands (B1,B2,B3,B4) at nanometric scale. These results were compared with those of the Silicon (Si) which was selected like reference. Then we plotted the curves of energy according to volume with the software Origin version 6 after having to make a tittle program in language Fortran 97 which calculates volume according to the cell parameter. The interesting discoveries in the technology of the semiconductors encouraged us to make the same study with CdZnTe to see whether the fact of having zinc (Zn) with CdTe will pose a change in the results towards a more promising detection. All the theorical results that we obtained were compared with the experimental results of the scientific articles. This study must highlight new semiconductor materials which will answer the keyboard of loads of the detection of the radiations in general.
Keywords: detectors with semiconductors, semiconductor, CdTe, CdZnTe, DFT, LMTO, LDA | 17 3 |
| 17:45 | Detection of change in fluorescence between reactive cyan and the yellow fluorophores using a-SiC:H multilayer transducers Authors : P. Louro1,2, M. A Vieira,1,2, M Vieira1,2,3 Affiliations : 1Electronics Telecommunication and Computer Dept. ISEL, R. Conselheiro Emídio Navarro, 1949-014 Lisboa, Portugal Tel: +351 21 8317290, Fax: +351 21 8317114, mv@isel.ipl.pt ; 2 CTS-UNINOVA, Quinta da Torre, Monte da Caparica, 2829-516, Caparica, Portugal. 3 DEE-FCT-UNL, Quinta da Torre, Monte da Caparica, 2829-516, Caparica, Portugal Resume : The device consists of a p-i'(a-SiC:H)-n/p-i(a-Si:H)-n heterostructure optimized for the detection of the fluorescence resonance energy transfer between fluorophores with excitation in the violet (400nm) and emissions in the cyan (470nm) and yellow (615 nm) range of the spectrum. The thickness and the absorption coefficient of the i'- and i- layers were tailored for cyan and yellow optical confinement, respectively in the front and back photodiodes acting both as optical filters.
To simulate the FRET pairs and the excitation light a chromatic time dependent combination of violet, cyan and yellow wavelengths was applied to the device. The generated photocurrent was measured under negative and positive bias to readout the combined spectra. The independent bit sequences (8 bit per wavelength channel) were chosen in order to sample all the possible chromatic mixtures for a pulse rate of 6000bps. Different wavelength backgrounds were also superimposed. Results show that under appropriated steady state optical bias the sensor will detect separately the cyan and yellow fluorescence pairs. The ratio between both intensities is obtained without optical bias, which in turn can be correlated with the distance between the fluorophores. An electrical model, supported by a numerical simulation, gives insight into the transduction mechanism. | 17 4 |
| 17:45 | Enhancement of electroluminescence efficiency for SiNx light-emitting devices via silver island film Authors : Feng Wang, Dongsheng Li, Deren Yang, and Duanlin Que Affiliations : State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University Resume : Recent years, the applications of metal nanoparticles on light emitting devices (LEDs) have been received extensive attentions, which could improve their optoelectronic performance substantially. SiNx-based LED is a competitive candidate of Si-based light source for its lower carrier injection barriers and promising luminescence efficiency comparing with its counterpart SiOx-based LED. However, the extraction efficiency of electroluminescence (EL) from SiNx-based LEDs is still too low to achieve the demands of optical interconnections.
The improvements of EL efficiency of SiNx-based LEDs by depositing silver (Ag) island films on and underneath the luminous layer were achieved. We attributed these improvements to the increase in light extraction efficiency, internal quantum efficiency, and carrier injection efficiency. The increase of light extraction efficiency was resulted from the surface roughening of ITO electrode, which can be estimated semiquantitatively via total integrated scatter model. While we attributed the improvement of internal quantum efficiency to the enhancement of spontaneous emission rate due to the coupling between excitons in SiNx and localized surface plasmons. An obvious blue-shift of EL peaks was observed in our SiNx-based LEDs, and a reasonable explanation on this phenomenon as well as the origin of its EL were provided. We believe that our work represents an interesting and important contribution to the general area of SiNx- or Si-based LEDs. | 17 5 |
| 17:45 | SiC multilayer structures as photonic active filters Authors : M. A. Vieira1,3, M. Vieira1,2, P. Louro1,2, V. Silva1,2, A. Fantoni1,2 Affiliations : 1Electronics Telecommunication and Computer Dept. ISEL, R. Conselheiro Emídio Navarro, 1949-014 Lisboa, Portugal Tel: +351 21 8317290, Fax: +351 21 8317114, mv@isel.ipl.pt ; 2 CTS-UNINOVA, Quinta da Torre, Monte da Caparica, 2829-516, Caparica, Portugal. 3 DEE-FCT-UNL, Quinta da Torre, Monte da Caparica, 2829-516, Caparica, Portugal Resume : Combined tunable WDM converters based on SiC multilayer photonic active filters are analyzed. The operation combines the properties of active high-pass and low-pass filter sections into a capacitive active band-pass filter. The configuration includes two stacked p-i-n structures (p(a-SiC:H)-í'(a-SiC:H)-n(a-SiC:H)-p(a-SiC:H)-i(a-Si:H)-n(a-Si:H)) sandwiched between two transparent contacts. Transfer function characteristics are studied both theoretically and experimentally. A capacitive active band-pass filter model supports the experimental data. An algorithm to decode the multiplex signal is established.
Results show that the light-activated device combines the demultiplexing operation with the simultaneous photodetection and self amplification of an optical signal. The output waveform presents a nonlinear amplitude-dependent response to the wavelengths of the input channels. Depending on the wavelength of the external background it acts either as a short- or a long- pass band filter or as a band-stop filter. A two stage active circuit is presented and gives insight into the physics of the device. The device, modeled by a circuit with variable capacitors and interconnected phototransistors through a resistor is a current-control device. It uses a variable capacitance to control the power delivered to the load acting as a state variable filter circuit. It combines the properties of active high-pass and low-pass filter sections into a capacitive active band-rejection filter. | 17 7 |
| 17:45 | Tunable reflector based on random dispersed metallic nanorods Authors : Shiwei Shu, Yangyang Li Affiliations : Department of Physics and Materials Science City University of HongKong Resume : The magical optical properties of metallic nanostructures have attracted researchers' great interest——plasmonics, metamaterials, optical filters, solar cell concentrators and surface enhanced Raman scattering. As we known, rugate filters could provide a reflection peak caused by its periodicity along its longitudinal directions. In contrast to conventional dielectric rugate filters, metallic nanorods with rugate filter structures have better characteristics in high electrical conductivity, thermal conductivity and rich optical phenomena. Here, we have theoretically investigated the optical properties of metallic nanorods with rugate filter structures. The calculations are based on scattering matrix method (SMM) and finite-difference time-domain (FDTD) method. We demonstrated the tunable reflector could be tuned by periodicity in longitudinal direction, average metallic fraction ratio, amplitude of metallic fraction ratio. Furthermore, double peaks can be easily realized by adding metallic fraction functions which have different periodicities in longitudinal direction. The novel tunable reflector which can be fabricated easily nowadays has great potential applications in photoelectric devices. | 17 8 |
| 17:45 | Polarization dependant evanescent optical field interaction with atom and its effect on atomic emission spectra Authors : S. M. Iftiquar Affiliations : Department of Physics, Indian Institute of Science, Bangalore, India. (Present Address) School of Information and Communication Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, 440-746, Republic of Korea Resume : Evanescent optical field (EOF) plays an important role in localized excitation and electro-optic interaction in nano structures. Interestingly, it has been well known that sub-micron particles interact strongly with EOF. Among various factors influencing strength of this interaction, shape of the particle is one of them. In this report we present results of atomic interaction with polarized EOF. We have investigated emission spectra of rubidium (Rb) atoms in this respect. A constant frequency and intense EOF was created at a point (P) inside the glass wall of Rb vapor cell, which acts as a pump field for the Rb atoms that exist in the neighborhood of P. With the help of a frequency tunable probe laser beam, the stimulated emission spectra of the Rb atoms were detected by a photodiode, placed near the point P. We have observed that the peak intensity of emission spectra depends on polarization of the EOF, indicating effective interaction between the EOF and the Rb atoms may also depend upon the component of polarization vector, normal to the EOF creating surface. The results demonstrate that the strength of the EOF interaction with tiny particle can be controlled by altering polarization of the localized optical field. | 17 9 |
| 17:45 | Emission from an optical nanocavity coated with an ultra-thin film of fluorescent molecular dye Authors : Kieran Deasy, Stuart Brittle, Tim Richardson, David Lidzey Affiliations : Department of Physics and Astronomy, University of Sheffield, Sheffield, United Kingdom Resume : An optical nanocavity can be created by intentionally introducing a defect into a two-dimensional photonic-crystal. Here, we have explored fabricating optical nanocavities into a free standing silicon nitride membrane, with the cavity structure based on a so-called L3 structure (3 missing holes). Using FDTD simulations, we have designed our cavities to have a fundamental mode located at approximately 660 nm. As the active emissive material in our cavity, we utilized ultra-thin films of the fluorescent organic dye Lumogen Red that were coated onto the cavity surface (and the surrounding photonic crystal) using a Langmuir-Schaefer (LS) deposition technique. This technique permits molecular monolayers to be sequentially deposited onto a surface, providing precise control over film thickness. We have explored the effect of the thickness of the deposited film on the cavity emission, and show that fluorescence emission via the cavity mode (which has a Q-factor of 1800) can be readily detected from structures coated by a single molecular monolayer of Lumogen Red. We calculate that approximately 1,000,000 molecules coat the cavity surface of such structures. We will also discuss our strategy for the creation of structures containing a single emissive molecule. Such structures may have applications as chemical sensors, or as quantum information light-sources. | 17 10 |
| 17:45 | Optical properties of pulsed-laser deposited amorphous Ge films Authors : Arsen Y. Mkrtchyan Affiliations : Institute of RadioPhysics and Electronics, National Academy of Sciences, Republic of Armenia; Resume : Amorphous Ge films (thickness 25-450 nm) were obtained on the glass substrates at room temperature by the vacuum (3•10-6 mm Hg) pulsed laser (Q-switched glass: Nd3 laser: wavelength — 1.06 μm, pulse duration — 30 ns, intensity in the Ge target irradiation zone — ~109 W/cm2) deposition method in non-equilibrium conditions of growth. The optical properties of fabricated films were studied in the range of 400-1000 nm using a spectrometer Filmetrics F20. It was shown that the optical properties of the amorphous Ge films are explained by the Tauc model for amorphous semiconductors. It was also established that the optical gap of films depends on the thickness. | 17 11 |
| 17:45 | Near-field optical response of ion shaped gold nanoparticules embedded within a silica matrix. A theoretical description based on finite difference time domain scheme Authors : A. Fafin (1), J. Cardin (1), C. Dufour (1), P.-E. Coulon (2), G. Rizza (2), A. Slablab (2) Affiliations : (1) CIMAP, UMR CNRS/CEA/ENSICAEN/UCBN, 6 Bd Marchal Juin, 14050 Caen Cedex 4, France; (2) LSI, Ecole Polytechnique-CEA/DSM-CNRS, 91128 Palaiseau Cedex, France Resume : Since few years, an innovative and powerful technique for manipulating matter at the nanometer scale by ion-shaping has been investigated. This technique allows the deformation of metallic spherical particles embedded within an ion-deformable amorphous host matrix into prolate nanorods and nanowires.
The objective of this presentation is the theoretical study of the near-field optical response of gold nano objects within a dielectric silica matrix and compare it with the results obtained from electron energy-loss spectroscopy (EELS) experiments. We use a three dimensional finite difference time domain (FDTD) method to solve the Maxwell's equations. To model the dielectric properties of Au, we introduce a Drude-Lorentz oscillators model which is coupled to the FDTD method by a set of Auxiliary Differential Equations (ADE). Thus we can modelize the near-field response of different gold nano objects (spherical, nanorods, nanowires) in a range of energy from 0.5 eV to 6 eV and then calculate the local field enhancement factor i.e. the ratio of the amplitude of the total field over the incident field. The results for different gold nano-objects are in good agreement with the experimental results found by EELS. | 17 12 |
| 17:45 | Light control employing a diamond-based photonic crystal slab Authors : L. Ondic (1,2), M. Ledinský (1), K. Dohnalová (3), K. Kusová (1), O. Cibulka (1), O. Babchenko (1), A. Kromka (1), B. Rezek (1) and I. Pelant (1) Affiliations : (1) Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, CZ-162 53, Prague 6, Czech Republic; (2) IPCMS–DON Unité Mixte, UMR 7504, CNRS–ULP, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France; (3) Van der Waals–Zeeman Institute, University of Amsterdam, Valckenierstraat 65, NL-1018 XE Amsterdam, The Netherlands Resume : Diamond is a material with many potential optical, electronic and thermal applications. Nowadays, due to developed techniques of its preparation and patterning, its applicability in photonics is considered.
Here, we present a detailed analysis of photonic properties of a nano-diamond photonic crystal (PhC) consisting of a 270 nm thick nanocrystalline diamond layer with diamond columns (diameter 280 nm, height 150 nm ) prepared on the top and periodically ordered into the square lattice (lattice constant 350 nm). Photonic band diagram of the structure leaky modes is determined from angle and spectrally resolved transmission measurements. The results of measurements are in excellent agreement with a simulated photonic band diagram in broad spectral region showing that a strong light-matter interaction occurs in the PhC. The existence of leaky modes allows us to increase the extraction efficiency of the intrinsic diamond photoluminescence (PL) from color centers present in the PhC. Up to 6-fold enhancement occurs in the visible region which may be employed when constructing diamond LEDs or waveguide couplers/outcouplers.
We also demonstrate that the PhC could be used to control shape of the PL spectra of quantum dots deposited on its surface. It is pointed out that optical losses related with the absorption mechanism and scattering present in nano-diamond influences light interacting with the periodicity and must be taken into account when designing such a structure. | 17 13 |
| 17:45 | Surface role in efficient light emission from organically terminated Si quantum dots Authors : K. Dohnalova1, H. Zuilhof2, T. Gregorkiewicz1 Affiliations : 1 Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, NL- 1098 XH Amsterdam, The Netherlands; 2 Laboratory of Organic Chemistry, Wageningen University, Dreijenplein 8, 6703 HB Wageningen, The Netherlands Resume : Surface properties have crucial influence on the photoluminescence (PL) from
small quantum dots (QDs). This effect is further enhanced in Si-QDs by the low optical activity of the core due to the indirect band-gap. This has been illustrated and understood for systems of oxidized Si-QDs, however, up to now, effect of other terminations, such as nitrogen or carbon, remains unclear. It has been shown that the PL lifetime in Si-QDs terminated by alkyl molecules becomes three orders of magnitude faster than expected for the intrinsic excitonic emission. This cannot be explained by existing Si-QDs models. In this contribution, we show that the fast PL in the blue-green spectral region from wet chemically synthesized small Si-QDs (2-3 nm) terminated by alkyl molecules, takes place on both the ensemble and the single dot levels, which directly confirms its intrinsic Si-QD origin. Moreover, using theoretical modeling, we present evidence for that this emission arises due to efficient phonon-less radiative recombination. | 17 14 |
| 17:45 | Size-Scaling in Optical Trapping of Silicon Nanowires Authors : Alessia Irrera1, Pietro Artoni2,3, Rosalba Saija4, Pietro G. Gucciardi1, Maria Antonia Iatì1, Ferdinando Borghese4, Paolo Denti4, Fabio Iacona2, Francesco Priolo2,3, and Onofrio M. Maragò1 Affiliations : 1CNR-IPCF, Istituto per i Processi Chimico-Fisici, I-98158 Messina, Italy 2MATIS-IMM CNR, I-95123 Catania, Italy 3Dipartimento di Fisica e Astronomia, Università di Catania, I-95123 Catania, Italy 4Dipartimento di Fisica della Materia e Ingegneria Elettronica, Università di Messina, I-98166 Messina, Italy Resume : We investigate size-scaling in optical trapping of ultrathin silicon nanowires showing how length regulates their Brownian dynamics, optical forces, and torques. Force and torque constants are measured on nanowires of different lengths through correlation function analysis of their tracking signals. Results are compared with a full electromagnetic theory of optical trapping developed in the transition matrix framework, finding good agreement1.
1 Irrera et al., Size-scaling in optical trapping of silicon nanowires, Nanoletters 2011, 11, p 4879 | 17 15 |
| 17:45 | Garnets nanophosphors prepared by sol-gel method for application in optoelectronics Authors : Vasilica Schiopu, Alina Matei, Ileana Cernica Affiliations : National Institute for Research and Development in Microtechnologies, IMT Bucharest Resume : Today, the most known system to obtain the white light-emitting device is based on the combination of a yellowish phosphor and a blue chip. The phosphors from garnets class are still the most known and efficient for use in optoelectronics applications. In this paper is presented the same sol-gel method as a route to producing two diffrent types of garnets phosphors at nanoscale. The phosphors nanoparticles and the formation of the garnet phase have been obtained at lower temperature then conventional methods. The chemical evolution, structure and morphology of rare earth-doped YAG (yttrium aluminum garnet) and TAG (terbium aluminum garnet) were studied. | 17 16 |
| 17:45 | Optical filter design using background wavelength processing techniques Authors : M. Vieira1,2,3, M. A. Vieira1,2, P. Louro1,2, A. Fantoni1,2, A.S. Garção2,3 Affiliations : 1Electronics Telecommunication and Computer Dept. ISEL, R. Conselheiro Emídio Navarro, 1949-014 Lisboa, Portugal 2 CTS-UNINOVA, Quinta da Torre, Monte da Caparica, 2829-516, Caparica, Portugal. 3 DEE-FCT-UNL, Quinta da Torre, Monte da Caparica, 2829-516, Caparica, Portugal Resume : Experimental and simulated results are compared to validate the use of SiC multilayered structures in applications where gain compensation is needed or to attenuate unwanted wavelengths, as well as in building blocks for band-pass filters used for channel or band selection in WDM communication systems. An electrical model supports experimental results
Color pulsed communication channels are transmitted together under different background wavelength. Amorphous SiC tandem heterostructures are used to filter a specific band. Results show that under controlled wavelength backgrounds the device sensitivity is enhanced in a precise wavelength range and quenched in the others, tuning or suppressing a specific band. Under red irradiation the transfer function has a higher gain at short wavelengths than at longer wavelengths acting as a short-pass filter whatever the frequency. Under green the device is a band-rejection active filter that works to screen out wavelengths that are within the medium range (550nm), giving easy passage at all wavelengths below (450 nm) and above (650 nm). Under blue steady state optical bias the device behaves as a long-pass active filter that transmits and enhances the long wavelength photons (red and green channels) while blocking the shorter wavelengths (blue channel). Particular attention is given the transition of a short-pass optical filter to a band-rejection filter, which allows any photo capacitance response to be provided. | 17 17 |
| 17:45 | Enhanced blue emission of GaN:Eu2 with increasing SiO2 nanoparticles under a flowing NH3 atmosphere Authors : Bong Kyun Kang, Myung-Oh Kim, Dae Ho Yoon Affiliations : Sungkyunkwan University Resume : In recent years, III-nitrides nanostructures have attracted extensive attention due to their unique electronic and optical properties. Gallium nitride (GaN) has a direct wide bandgap of 3.4 eV at room temperature, and is a promising candidate material for short wavelength optoelectronic devices, such as light emitting diodes and laser diodes, as well as high power and high temperature operation devices. Forthermore, rare earth-doped GaN have a promising applications as multiple color electroluminescent (EL) devices due to the chemical stability and a large incorporation of rare earth dopants such as Eu, Er, Tb, Tm. In case of Eu ions in host materials, it has a distinctive optical property which was commonly observed strong and shape emission at around 612 nm by the f-f transitions of Eu3 ions, on the other hand, the Eu2 ions showed broad blue emission at around 450 nm, depending on the environments around the Eu ions such as in aluminates, silicate matrices. Despite the large number of reports on the synthesis of rare earth doped GaN over the past few years, most reports focused on the rare earth doped GaN film and nanowires by MOCVD, MBE, MOVPE and thermal CVD. Compared with film and nanowires, GaN nanopowder could be alternative hybrid integration materials with a variety of optical properties because of the flexible powder form and controlled shape or size, as well as low fabrication cost.
GaN:Eu2 added SiO2 nanoparticles were synthesized successfully nitridation of Eu3 -doped gallium oxide with SiO2 nanoparticles. We report on the synthesis and characterization of the GaN:Eu2 added SiO2 nanoparticles as a function of SiO2 amounts. The structural and optical properties of GaN:Eu2 added SiO2 nanoparticles were examined as well. | 17 18 |
| 17:45 | Indium-zinc-oxide transparent electrode for nitride-based light-emitting diodes Authors : S. Mizutani,S. Nakashima, M. Iwaya, T.Takeuchi, S. Kamiyama, I. Akasaki , T. Kondo, F.Teramae, A. Suzuki, T. Kitano, M. Mori, M.Matsubara Affiliations : Faculty of Science and Technology, Meijo University, 1-501 Shiogamaguchi, Tenpaku-ku, Nagoya 468-8502, Japan EL-SEED, Corp., Furocho, Chikusa-ku, Nagoya 464-8601, Japan Idemitsu Kosan Co., Ltd. 1280, kamiizumi, sodegaura, 299-0293, Japan Resume : In general nitride-based light-emitting diodes (LEDs), an indium-tin-oxide (ITO) thin film is used as a transparent ohmic contact to p-GaN, and it contributes to an enhancement of light extraction efficiency. However, the ITO has a microcrystalinity, so that it makes difficult to form nano-patterning for further improvement of the light extraction efficiency. In this paper, a new transparent electrode material, amorphous indium-zinc-oxide (IZO) is proposed for micro-fabrication.
A 300 nm-thick IZO (In2O3 : ZnO=0.893:0.107, wt%) film was deposited on p-GaN and sapphire substrates by a reactive sputtering technique. A voltage versus current characteristic showed ohmic property, and contact resistance was 9.4×10^-4 ohmcm^2, which is comparable to that of ITO. And other physical properties such as a resistivity of 2.5×10^-4 ohmcm and a high transmittance of more than 80% at 450 nm were obtained with IZO/sapphire samples. These properties show sufficient potentials of IZO as a transparent electrode material to nitride-based LEDs. In addition, since the IZO film has an amorphous phase with a mirror-like surface, formation of fine nano-patterns is possible. We succeeded to form a moth-eye structure with a pitch of 460 nm to IZO transparent contact on a nitride-based LED, and it is expected higher output power than the LED before the moth-eye structure formation. | 17 19 |
| 17:45 | Electroluminescent properties of third generation fluorene-carbazole dendrimers Authors : Ozlem Usluer,1* Serafettin Demic,2 Mahmut Kuş,3 Yasin Kanbur,4 Eckhard Birckner,5 Daniel A. M. Egbe6 and Niyazi Serdar Sariciftci6 Affiliations : 1Department of Chemistry, Science Faculty, Mugla University, 48000, Mugla (Turkey) 2Solar Energy Institute, Ege University, Bornova, Izmir (Turkey) 3Chemical Engineering Department and Avdanced Technology R&D Center, Selcuk University, Konya (Turkey) 4Department of Metallurgical and Materials Engineering, Faculty of Engineering, Karabük University, Karabuk (Turkey) 5Institute of Physical Chemistry, Friedrich Schiller-University Jena, Lessingstrasse 10, 07743, Jena (Germany) 6Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Johannes Kepler University, Altenbergerstr. 69, A-4040 Linz (Austria) Resume : This work presents the synthesis, characterization and OLED applications of hole-transporting dendrimeric molecules (OFC-G3, OFCT-G3, SBFC-G3, SBFCT-G3) containing dioctylfluorene and spirobi(fluorene) as the core unit and different numbers of carbazole and thiophene moieties as the peripheral groups. The chemical structure of the dendrimers were confirmed by 1H NMR, 13C NMR, FTIR and MALDI-TOF. The photophysical properties were investigated by UV-Vis absorption and photoluminescence measurements in dilute chlorobenzene solution as well as in thin film. Fluorescence kinetics measurements in solution were performed. The electrochemical behavior of the dendrimers were investigated by cyclic voltammetry (CV). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to study the thermal behavior of the materials. OLED devices were fabricated with a configuration of ITO/PEDOT:PSS/Dendrimer/Alq3/LiF:Al where OFC-G3, OFCT-G3, SBFC-G3 and SBFCT-G3 were used as hole-transporting layer, Alq3 as a light emitting and electron-transporting layer, ITO and LiF:Al as anode and cathode, respectively. All dendrimers exhibited bright green light emission between 512-528 nm and SBFCT-G3 showed maximum performance with a turn-on voltage of ~2.5 V and maximum luminance of 16000 cd/m2.
*Özlem Usluer,
Tel.: +90 252 211 15 62, FAX: +90 252 211 14 72
Email: usluerozlem@yahoo.com.tr, ousluer@mu.edu.tr | 17 20 |
| 17:45 | Surface modification of CdSe/ZnS quantum dots and layer-by-layer deposition of quantum dots Authors : Eun Yee Ko1,2, Ju-Won Jeon2, In Hwan Lee2, and Joo In Lee1,* Affiliations : 1Nano imaging technology center, Korea Research Institute of Standards and Science, Daejeon, Korea 2School of Advanced Materials Engineering and Research Center of Advanced Materials Development, Chonbuk National University, Jeonju, Korea Resume : This paper reports on the modification of ZnS capped CdSe quantum dots (QDs) surface with polyelectrolyte coating and monolayer subsequent layer-by-layer (LBL) deposition. The initial capping ligand is replaced by a hydrophilic thiol-containing ligand (MAA) which renders the QDs negatively charged in water. Subsequent layers of positive (PAA) is deposited on the QD surface, thereby modifying the surface charge. While many deposition methods have been demonstrated, it is still remain as a challenging to monolayer on substrate. In order to fabricate the QD-LED, we explored the formation of charge-driven LBL assemblies of cationic-anionic QD bilayers on anionic GaN substrate. The modified QDs were deposited on GaN substrates to produce self-assembled layer-by-layer deposition (QDs-MAA/QDs-PAA/GaN substrate), as revealed by photoluminescence. As a result of PL, we observed QDs emission peak and phonon replicas. This simple and robust technique could be chemically modified QD surfaces by controlling the external surface charge and thickness of the deposited layers. | 17 21 |
| 17:45 | Hyperspectral near-field imaging for nanophotonics Authors : Jean Dellinger, Loic Lalouat, Benoît Cluzel, Frédérique de Fornel Affiliations : Groupe d'Optique de Champ Poche Université de Bourgogne Resume : The scanning near-field optical microscopy (SNOM) is used to analyze optical phenomena at the sub-wavelength scale such as light localization and propagation in photonic crystals or plasmonic devices. In any case, SNOM experiments rely on the positioning of a local probe in the optical near field of a given structure and on the detection of the surrounding evanescent waves. Depending on the nature of the probe or on the optical detection method, the detected physical properties are the spatial distributions of the amplitude and phase or the intensity of the electric and magnetic components of the probed field. In this paper, we present the implementation of an innovative hyperspectral near-field imaging method which aims to detect both spectral and spatial properties of an optical nanosystem at the subwavelength scale. The presented method provides a batch of images over a broad spectral range at visible; near-infrared and telecommunication wavelengths. Using this technique, we will report here the near-field observations through the spectrum of the emblematic electromagnetic phenomena involved in photonic crystals and plasmonics such as light waveguiding, trapping or beam shaping. | 17 22 |
| 17:45 | Waveguiding and light confinement in gallium oxide nanowires Authors : I. López, E. Nogales, B. Méndez and J. Piqueras Affiliations : Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain Resume : Gallium oxide micro- and nanostructures have been used to demonstrate waveguiding behavior and light confinement of excited luminescence enabling the appearance of optical resonant modes. Cr3+ ions exhibit a well-known red emission and were used as luminescence centers in Ga2O3 nanostructures. The strong electron-phonon coupling in gallium oxide leads to a broad red emission band along with characteristic sharp lines at room temperature. This feature would be interesting for applications of these structures as tunable lasers. The experiments have been carried out in a scanning electron microscope operating in the angle resolved cathodoluminescence (ARCL) mode. An optical confocal Raman microscope with the possibility of recording data from a deviated point respect to the excitation one has also been used to explore the light coupling in crossing and interconnected nanowires. Resonances in the luminescence spectra have been observed and the results were explained in the framework of light confinement into the nanostructures. | 17 23 |
| 17:45 | Electroluminescence from SOI photonic crystals cavities at telecommunication wavelengths Authors : P. Cardile1, A. Shakoor2, R. Lo Savio3, S. L. Portalupi3, D. Gerace3, K. Welna2, S. Boninelli1, G. Franzò1, F. Priolo1, T. F. Krauss2, M. Galli3, and L. O’Faolain2 Affiliations : 1) CNR-IMM MATIS and Dipartimento di Fisica e Astronomia, Università di Catania, via S. Sofia 64, 95123 Catania, Italy 2) SUPA, School of Physics and Astronomy, University of St. Andrews, Fife KY16 9SS, St. Andrews, United Kingdom 3) Dipartimento di Fisica “A. Volta,” Università di Pavia, 27100 Pavia, Italy Resume : Photonic crystals represent an important tool in photonics, for the very high number of applications in which they are used. In this work we realized an electroluminescent Silicon pin-like device based on L3 photonic crystal membraned nanocavities, in which the Purcell effect is used.
We present and compare photo- and electro-luminescence from our devices, in which hydrogen-related defects are introduced by a plasma treatment in a reactive ion etching system. We believe that the recorded luminescence is related to the presence of these defects. The luminescence shape is broad and it falls in the near infrared (around 1.5 um), thus being promising for feasible applications. We show also that it is strongly enhanced in the L3 cavities, due to Purcell effect. TEM measurements were done in order to analyze the structural features of plasma-induced defects and to correlate them to the luminescence. We also performed an electrical characterization of the devices, demonstrating a good carrier injection. We believe that our study is a promising approach to a future Silicon nanolaser. | 17 24 |
| 17:45 | Extending a Parabolic Mirror – Scanning Near-Field Optical Microscope (PM-SNOM) with the functionality of a Scanning Tunneling Microscope (STM) Authors : Jan Rogalski, Kai Braun, Dai Zhang, Alfred Meixner Affiliations : Eberhard Karls University Tuebingen -Institute of Physical and Theoretical Chemistry; Resume : Scanning near-field optical-Microscopes are capable of breaking the far field resolution limit by analyzing the evanescent light emitted from a small region between the sample surface and a metal-tip. Our group has longstanding experience in operating a PM-SNOM that uses a parabolic mirror (PM) as focusing element. Recently this microscope has been extended by introducing scanning tunneling microscope (STM) functionality.
The newly added module exhibits a high position-accuracy and –stability coupled with a low fluctuation rate of the tunneling current. The implementation of the STM-module into a PM-SNOM setup furthermore allows for the simultaneous capturing of the optical signal and the corresponding local spectroscopic information.
Enhanced Raman spectroscopy measurements of 1H-Benzotriazole (BTAH) on a 200 nm thin gold-layer are used to demonstrate the functionality of the STM-module, which displays a Raman enhancement factor of ~2•10^5. Additionally, topographic measurements on a thin gold-layer with the module result in images typical for thin layers of evaporated gold. The concurrently obtained optical signal shows the shinning-edge effect on protrusions of the rough sample surface.
The extended PM-SNOM is used to examine pristine graphene, graphene – molecule interactions in a graphene-pentacene system, as well as graphene edges and defects. First confocal and near-field measurements of graphene obtained with the setup will be shown. | 17 25 |
| 17:45 | Controlling the emission rate of Er3+ ions by the interaction with thin films or plasmonic nanostructures Authors : B. Kalinic, T. Cesca, G. Perotto, C. Scian, P. Mazzoldi, G. Mattei Affiliations : CNISM and University of Padova, Dept. of Physics and Astronomy, via Marzolo 8, I-35131 Padova (Italy) Resume : The variation of the local density of states and/or excitation of surface plasmons in proximity of a metal or dielectric surface can be used to enhance and control the emission rate of Er-doped materials for nanophotonic or plasmonic devices.
In the present work we study the modification of the radiative lifetime of a rare earth emitter (Er3+ ion) in silica through the interaction with a plasmonic or a dielectric thin film.
A thin Er-doped silica film obtained via magnetron co-sputtering was coated with noble metal (Ag and Au) or dielectric (TiO2) films. Photoluminescence (PL) measurements have showed in both cases a strong decrease of the Erbium lifetime for the radiative transition at 1540 nm (up to 3 times) and a clear decrease of the interaction with the addition of a silica spacer between the film and the active layer up to 250 nm. Moreover, the effect on the PL emission of the continuous films has been compared with that of nanostructured plasmonic architectures like nanohole arrays (NHA) or nanotriangles arrays (NTA) deposited by nanosphere lithography and/or reactive ion etching on top of the active layer.
We have demonstrated that a good control over the radiative properties of the emitter can be achieved by a careful design of the nanostructures. | 17 26 |
| 17:45 | Site specific (EF)TEM characterization of Er3+ implanted silicon nanoelectro-optical devices Authors : L. López-Conesa, J.M. Rebled, S.Estradé, Y. Berencén, F. Ferrarese Lupi, J.M. Ramírez, B. Garrido, J.-M. Fedeli and F.Peiró Affiliations : MIND-In2UB, Electronics Department, University of Barcelona (UB), Martì i Franquès 1, Barcelona 08028, Spain; MIND-In2UB, Electronics Department, University of Barcelona (UB), Martì i Franquès 1, Barcelona 08028, Spain and Institut de Ciència de Materials de Barcelona (ICMAB), CSIC, Campus UAB, Bellaterra 08193, Spain; MIND-In2UB, Electronics Department, University of Barcelona (UB), Martì i Franquès 1, Barcelona 08028, Spain and Scientific and Technological Centers, (CCiT), University of Barcelona, Solé i Sabarís 1, 08028 Barcelona, Spain; MIND-In2UB, Electronics Department, University of Barcelona (UB), Martì i Franquès 1, Barcelona 08028, Spain; MIND-In2UB, Electronics Department, University of Barcelona (UB), Martì i Franquès 1, Barcelona 08028, Spain; MIND-In2UB, Electronics Department, University of Barcelona (UB), Martì i Franquès 1, Barcelona 08028, Spain; MIND-In2UB, Electronics Department, University of Barcelona (UB), Martì i Franquès 1, Barcelona 08028, Spain; CEA, Léti, Minatec campus 17 rue des Martyrs, 38054 Grenoble cedex 9, France; MIND-In2UB, Electronics Department, University of Barcelona (UB), Martì i Franquès 1, Barcelona 08028, Spain Resume : Silicon nanophotonics is a highly active field [1-3]. The possibility to integrate optical devices in microelectronic chips using the cheap semiconductor fabrication methods is a great advantage. However, the main drawback is the difficulty to obtain efficient light emission from bulk Si-based materials. The presence of Si nanocrystals in SiO2 matrices has been proved to increase this efficiency in the visible light range, and the implantation of rare earths ions allows to shift this emission towards de 1550nm wavelength of the telecomunications range. Combining these active materials with the optical properties of circular resonant cavities it is possible to achieve a high optical gain.
In this work two different kinds of devices, a slot ring resonant cavity coupled to a slot waveguide and a CMOS transistor, have been studied by Energy Filtered Transmission Electron Microscopy (EFTEM). Samples for TEM were prepared using the lift-out technique in a Focused Ion Beam (FIB) equipment. This sophisticated sample preparation method is necessary in order to select the specific region of interest in the devices. Quality of the fabrication process, morphology and composition of the devices is assessed.
Two different strategies in the ring/waveguide active layers were studied. The first one consisted in a Si-rich SiO2 (SRO)/SiO2 multilayered structure with embedded Si nanocrystals. EFTEM filtering around the plasmon peaks of crystalline Si and SiO2 confirmed the successful growth of the structure and the presence of nanocrystals in the SRO. The second one consisted in a continuous High Temperature Oxide (HTO) top layer. Erbium implantation in this second case resulted in cluster formation a few nanometers inside the layer. In the CMOS transistor, a similar clusterization of Er implantation was found in the channel section.
[1] L. Pavesi, S. Gaponenko, and L. Dal Negro, eds. Towards the First Silicon Laser, NATO Science Series (Kluwer, 2003), Vol. 93.
[2] F. Ferrarese Lupi, et. al, Optics letters / Vol. 36, No. 8 / April 15, 2011
[3] R. J. Walters, G. I. Bourianoff, and H. A. Atwater, Nat. Mater. 4, 143 (2005) | 17 27 |
| 17:45 | Control of the Er-Er interactions for nanophotonic applications Authors : P. Cardile1, M. Miritello1, R. Lo Savio1 and F. Priolo1 Affiliations : 1) CNR-IMM MATIS and Dipartimento di Fisica e Astronomia, Universit?i Catania, via S. Sofia 64, 95123 Catania, Italy Resume : Rare earths are well known for their optical properties: they emit photons of many wavelengths, due to their 4f shell and therefore they have many applications in light emitting devices. Metal particles, placed close to these rare earth ions, strongly influence their emission, both increasing the impinging electric field and modifying the decay rate.
Among the rare earths, Erbium is one of the most studied, emitting photons at 1.55 um, a strategic wavelength for telecommunications.
In this work we realized thin films of Er-compounds, grown by magnetron co-sputtering, such as Y-Er and Yb-Er silicates, in which the amount of rare earth can be continuously tuned from 1020 to 1022 at/cm3. In this extended range of concentrations the Er-Er interactions, such as cross-relaxations, quantum cutting or upconversion, can be perfectly controlled.
These materials are very interesting for practical applications, since they are compatible with the Si platforms and they have a huge amount of active emitters. This is the key point for having strong photoluminescence intensities. Even higher optical efficiencies and longer lifetimes are expected, thanks to the stronger localized electromagnetic field and the modification of the decay rate, by coupling these emitters to metallic nanoparticles. Therefore we propose Er-compounds as potential candidate materials for plasmonic applications. | 17 28 |
| 17:45 | Nanostars as nonlinear plasmonic rulers Authors : M. Kuttge (1), L. Rodriguez-Lorenzo (2), R. Alvarez Puebla (2), L. Liz Marzan (2), C. David (3), F. Javier Garcia de Abajo (3), N.F. van Hulst (1)(4) Affiliations : (1) ICFO – The Institute of Photonic Sciences, Castelldefels (Barcelona), Spain; (2) Departamento de Quimica-Fisica and Unidad Asociada CSIC-Universidade de Vigo, Vigo, Spain; (3) Instituto de Quimica-Fisica - CSIC, Madrid, Spain; (4) ICREA - Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain Resume : We demonstrate a nonlinear plasmonic ruler based on subnanometer distance control of plasmonic nanogaps between gold nanostars and gold surfaces. Furthermore, we show efficient coupling between light and surface plasmons mediated by nanostars.
Nanostars were attached to the surface using dithiol linkers and the second harmonic generation was measured upon illumination by fs-laser pulses. By varying the linker molecules were were able to change spacing from 1.5 nm to below 1 nm and observe a resulting five times increase of the second harmonic generation. Boundary element method calculations of the SHG confirm that this effect is due to increase in the field enhancements at the star-tip closest to the surface, as the nanostars are placed closer to the surface.
Additionally, we present measurements of the surface plasmon propagation in random arrays of gold nanostars placed on a gold surface. SPPs are excited by focusing a fs-laser beam onto single nanostars or grating couplers, which were created by focused ion-beam milling. The SPPs propagate along the surface and excite other nanostars, whose two-photon luminescence was imaged using a CCD camera. From these measurements we were able to extract coupling parameters of nanostars between SPPs and light and their respective scattering length. | 17 29 |
| 17:45 | HRTEM microstructure study and PL properties of Sn1-xMxO2 (M = V, Cr and Mn) nanoparticles Authors : M.A. Peche-Herrero1, D. Maestre2, J. Ramirez-Castellanos1, A. Cremades2, J. Piqueras2, and J. Gonzalez-Calbet1. Affiliations : 1. Department of Inorganic Chemistry I, Facultad de Cc. Qu?cas, Universidad Complutense de Madrid, Madrid (Spain). 2. Department of Material Physics, Facultad de Cc. F?cas, Universidad Complutense de Madrid, Madrid (Spain). Resume : Tin dioxide, SnO2, with rutile structure have been widely used as catalysts for CO oxidation, dye-sensitised solar cells and semiconductor gas sensors, due to to their electrical, optical, electrochemical properties and high chemical stability. Many techniques have been utilised to prepare nanopowders such as sol–gel, and hydrothermal methods. One approach to modify the optical properties of the nanoparticles is to introduce a small amount of a dopant inducing tuneable luminescence emission
According to these ideas, we have prepared Sn1-xMxO2 (M = V, Cr and Mn, 0≤x≤0.15) rutile solid solutions by a polymeric precursors method at 450 oC. The unit cell of SnO2 rutile structure is tetragonal (S.G. P42/mnm) with lattice parameters a=4.74 and c= 3.19 A, as confirmed by X ray diffraction (XRD). The average grain size of the prepared SnO2 nanoparticles is about 7 nm, as calculated by using the Scherrer formula. The luminescence properties of these samples have been analyzed by means of cathodoluminescence in a scanning electron microscope (SEM). Tuneable emission in the visible and the near-infrared range has been observed as a function of the dopant and the defects in the host lattice. The resulting sample was characterized and analyzed by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and high-resolution transmission electronmicroscopy (HRTEM). Light-emitting properties were measured by PL spectra. | 17 30 |
| 17:45 | Experimental evidences of energy transfer between Si nanoclusters and Er3+ ions under electrical pumping Authors : J.M. Ramírez1, F. Ferrarese Lupi1, O. Jambois1, Y. Berencén1, D. Navarro-Urrios1,4, A. Anopchenko2, A. Marconi2, N. Prtljaga, A. Tengattini2, , L. Pavesi2, J-P. Colonna3, J-M. Fedeli3 and B. Garrido1. Affiliations : 1 Departament d'Electrònica, Universitat de Barcelona, Carrer Martì i Franquès 1, Barcelona 08028, Spain. 2 Nanoscience Laboratory, Department of Physics, University of Trento, Via Sommarive 14, Povo (Trento) 38123, Italy. 3 CEA, Léti, Minatec campus 17 rue des Martyrs, 38054 Grenoble cedex 9, France. 4 Catalan Institute of Nanotechnology (CIN2-CSIC), Campus UAB, Edifici CM3, 08193 Bellaterra, Spain Resume : The development of efficient silicon based light sources emitting at 1.5 um has been under intense investigation for several years, providing important breakthroughs towards their implementation in optical interconnects and telecommunications [1]. In that context, Er3+ doped devices have demonstrated to be a good candidate, especially when sensitized with Si-nanoclusters (Si-ncs). Nevertheless, while such sensitization has been demonstrated under optical pumping [2], the efficient coupling between silicon nanocrystals and Er3+ ions under electrical pumping is still a matter of concern as no strong evidences have been elucidated yet.
In this work, Si-based metal-oxide-semiconductor light emitting devices containing Er3+ ions embedded in either stoichiometric SiO2 or silicon-rich silicon oxide layers have been studied. An electro-optical characterization has been performed first under direct current regime (DC) and compared with the ones obtained by means of a square alternate current excitation signal (AC). Two different EL excitation mechanisms have been observed for the coupled system with Si-ncs and Er3+: i) Indirect excitation: cold carriers excite Si-ncs by bipolar injection and the energy is transferred to Er3+ and ii) Direct excitation: Er3+ is directly energized by hot energetic carriers through impact excitation. Moreover, we demonstrate the existence of a narrow voltage window, where the Er3+ excitation mechanism changes from energy transfer to direct impact excitation.
[1] O. Jambois, F. Gourbilleau, A. J. Kenyon, J. Montserrat, R. Rizk, and B. Garrido; 2010 Opt. Express 2230, (2010).
[2] D. Navarro-Urrios, A. Pitanti, N. Daldosso, F. Gourbilleau, R. Rizk, B. Garrido, and L. Pavesi Phys. Rev. B 79, 193312 (2009) | 17 31 |
| 17:45 | The transition from surface defect passivation to donor activation in size controlled Si-nanocrystals doped with phosphorus Authors : N. Papachristodoulou[1], I. F. Crowe[1], M. P. Halsall[1], P. Yang[2], R. M. Gwilliam[2], M. Shah[3], A. J. Kenyon[3], O Hulko[4], A.P. Knights[4] Affiliations : [1] Photon Science Institute, Alan Turing Building, University of Manchester, Manchester M13 9PL, UK [2] Surrey Ion Beam Centre, Advanced Technology Institute, University of Surrey, Guildford, GU2 5XH, UK [3] Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, UK [4] Department of Engineering Physics, McMaster University, 1280 Main Street West, Hamilton L8S 4L7, Ontario, Canada Resume : We report a comparative study of the integrated PL intensity and emission energy for phosphorus (P) doped and intrinsic Si-nanocrystals (Si-nc). Our data suggest that the level of donor activation is highly sensitive to the Si-nc size distribution. For example, doped Si-ncs, with a relatively small mean size, exhibit an enhanced, blue-shifted PL, compared with intrinsic Si-ncs. This suggests that the P atom preferentially performs a passivating function, compensating for dangling-bond defects (Pb-centres), as previously evidenced by electron paramagnetic resonance (EPR) studies [1, 2]. As the Si-nc size increases, however, the ionization of P donors opens up an efficient, non-radiative Auger recombination channel for photo-excited carriers and the PL is quenched. Evidence for this can also be found in previous EPR and optical absorption data, both of which indicate an increase in the free carrier concentration with P doping [3, 4]. Controlling the size distribution, e.g. by rapid thermal processing, therefore provides a means for controlling the dopant activation in future silicon nano-structured electronic devices.
References
[1] Fujii et al, Journal of Applied Physics 87, 1855 (2000)
[2] Stegner et al, Physica B: Condensed Matter, 401-402, 541 (2007)
[3] Sumida et al, Journal of Applied Physics 101, 033504 (2007)
[4] Mimura et al, Physical Review B 62, 12625 (2000) | 17 32 |
| 17:45 | Nanooptical study of plasmonic nanoantennas by EELS and Cathodoluminescence spectroscopy Authors : Zackaria Mahfoud, Odile Stefan, Anne-laure Baudrion, Jérôme Plain, Mathieu Kociak Affiliations : Laboratoire de Physique des Solide, Orsay France and Université de Technologie de Troyes, Troyes France; Laboratoire de Physique des Solide, Orsay France; Université de Technologie de Troyes, Troyes France; Université de Technologie de Troyes, Troyes France; Laboratoire de Physique des Solide, Orsay France Resume : Plasmonic devices such as optical antennas operating in the visible region of the electromagnetic spectrum are constrained to spatial dimensions of a few nm to hundreds of nm. In particular, dimer nano-rod antennas have attracted increasing interest in recent years. Indeed, the coupling of rods induces modifications in the optical response which can be precisely adjusted by controlling the dimensions of the gap. The energies and intensities of the plasmon modes and the electric field associated can all be affected. Since most of these effects occur at the sub-wavelength scale, it is necessary to use techniques which allow us to probe this type of object at the nanometer scale.
We have performed Electron Energy-Loss Spectroscopy (EELS) and Cathodoluminescence (CL) spectral imaging in the UV-Vis-IR regime in a Scanning Transmission Electron Microscope (STEM) to study plasmons at nanometer spatial resolution on several types of coupled and uncoupled nanorods, either lithographed or chemically grown. The results of such experiments can be analyzed to map the spatial distribution of the energies, intensities and full width at half-maximum of the plasmons on nanoparticles. As an example EELS spectra acquired on a dimer nano-rod antenna show a blue-shift in the energy of the first plasmon peak inside the gap in comparison with the peak observed at the outer edge of the dimer, the shift is due to the coupling of the plasmons of the rods. | 17 33 |
| 17:45 | High optical quality width-modulated waveguide AlN photonic crystal nanocavities Authors : D.Sam-Giao1, D. Néel2, M. J. Rashid3, C. Brimont4, T. Bretagnon4, M. Mexis4, X. Checoury2, S. David2, F. Semond3, B. Gayral1, P. Boucaud2, T. Guillet4 Affiliations : 1 CEA-CNRS group “Nanophysique et semiconducteurs,” INAC-SP2M, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France 2 Institut d’électronique Fondamentale, UMR CNRS 8622, Université Paris Sud-11, F-91405 Orsay, France 3 CRHEA-CNRS, Rue Bernard Grégory, 06560 Valbonne, France 4 Université Montpellier 2, Laboratoire Charles Coulomb, CNRS UMR 5221, F-34095 Montpellier, France Resume : Due to their wide bandgap and large excitonic binding energy, nitride semiconductors are good candidates for UV microlasers or room temperature strong coupling in strongly confining microcavities. Nitrides are however very difficult to process, so that the fabrication of high quality photonic crystals is very challenging.
We report on the first top-down fabrication of high quality suspended width-modulated waveguide photonic crystal cavities in the low-index material AlN. The 70 nm thick AlN slab is grown by ammonia-source molecular beam epitaxy on a Si (111) wafer, with one layer of GaN quantum dots grown at the center of the slab. The structures are then defined by e-beam lithography (typical periodicity 170 nm and hole diameter 85 nm) and dry-etched by inductively coupled plasma. The membranes are then released by selective etching of the Si substrates.
Photonic crystal cavities were then studied by room-temperature microphotoluminescence (typical spot size: 1 µm). The best results were obtained on cavities inside a W1 photonic crystal waveguide, obtained by shifting a few holes away from the waveguide line defect. Quality factors in the 3000-4000 range were routinely obtained in the 3.2-3.5 eV (350-390 nm) range, the best result being 4500 - twice the maximum value obtained on L3 cavities with the same process. FDTD simulations reproduce well the spectral features we observe.
Prospects for microlasing and strong coupling will be discussed. | 17 34 |
| 17:45 | Enhancement of negligible transmission band using hybrid periodic/Fibonacci one dimensional photonic crystal in near infrared and microwave domains Authors : Abir Mouldi; Mounir Kanzari Affiliations : Laboratoire de Photovolta?e et Mat?aux Semi-conducteurs -Ecole Nationale d'Ing?eurs de Tunis Resume : The combination of periodic and quasi periodic one dimensional photonic band gap structures was the subject of many works. The approach has been generally explored to design resonant microcavities with strong mode localization or polychromatic filters. In this work, we propose to use this approach to enlarge the photonic band gap under grazing angles. We demonstrate the efficiency of the hybrid structure of the type Bragg mirror-(Fibonacci)S-Bragg mirror, with S is the repetition number of the Fibonacci block, to enhance the zero transmission band through the one dimensional photonic crystal in comparison with the periodic structure and the quasi periodic structure built according to the pattern of the Fibonacci sequence. The efficiency of the configuration is proved in microwave domain and in the near infra red range. In microwave domain, we achieve under normal incidence a broad band which covers almost all the domain, but the omnidirectional Photonic Band Gap exists only for angles below 57°. In the near infra red, the proposed design exhibits a large photonic band gap at any angle of incidence under the two modes of polarization, Transverse Magnetic and Transverse Electric. The achieved omnidirectional photonic band gap is larger than that of the periodic structure with an increasing ratio of 4.3 and it covers all the optical telecommunication wavelengths 0.85, 1.3 and 1.55 µm. The proposed structure is a quarter wavelength mirror of only 53 layers. So, unlike the previous devices, the structure is simple to fabricate and it shows very interesting optical properties. To deepen the study, we investigate the sensitivity of the system optical response to the configuration parameters which are the repetition number S, the generation number of the Fibonacci sequence and the period’s number of the two sidewall periodic stacks. The proposed system is a good candidate for the improvement of optoelectronic devices. | 17 35 |
| 17:45 | Near-field study of the generation and launching of surface plasmons at Telecom wavelengths Authors : L. Greusard*1, R. Rungsawang1, Y. De Wilde1, A.2, D. Costantini2, R. Colombelli2, J. Decobert3, J.-L. Gentner3, A. Accard3, G. H. Duan3 Affiliations : 1 Institut Langevin, ESPCI ParisTech, CNRS, 10 rue Vauquelin, 75231 Paris Cedex 05, France; 2 Institut d’Electronique Fondamentale, Université Paris Sud and CNRS, UMR8622, 91405 Orsay, France; 3 III-V Lab, Joint lab of 'Alcatel-Lucent Bell Labs France 'Thales Research and Technology' and 'CEA Leti‘ Route de Nozay, 91461 Marcoussis cedex, France Resume : Three main techniques are available for the excitation of Surface Plasmons (SPs): total internal reflection via prism coupling; scattering from a topological defect; use of a metallic grating. A compact electrical device capable of SP generation and injection into passive components would represent a major step towards “integrated active plasmonics”.
Such a device, using a quantum cascade laser, has been demonstrated for operation at mid-infrared wavelengths [1]. A numerical investigation has been performed [2] to design such a device at Telecom wavelengths (λ = 1.3 µm). We present a direct experimental demonstration of an efficient generation and launching of SPs at these wavelengths. We have reproduced the slit doublet experiment with SPs generated in situ with a laser diode by means of metallic gratings which couple the waveguided laser mode into a SP mode guided at Gold/Air interface.
Our observations use a modified commercial aperture near-field scanning optical microscope (WITec GmBH), whose probe features an aluminum hollow pyramid. Besides its interest for active plasmonics, this study shows the possibility of achieving near-field imaging with this type of microscope in the near-infrared range.
[1] A. Babuty, A. Bousseksou, J-P. Tetienne, I. Moldovan - Doyen, C.Sirtori, G. Beaudoin, I. Sagnes, Y. De Wilde, R. Colombelli, Phys. Rev. Lett. 104, 226806 (2010).
[2] J-P. Tetienne, A. Bousseksou, D. Costantini, R. Colombelli, Y. De Wilde, Opt. Express 19, 18155-18163 (2011) | 17 36 |
| 17:45 | Metal patterning on a TM semiconductor gain medium for plasmonic applications Authors : D.Costantini1, A.Bousseksou1, L. Greusard2, R. Rungsawang2, Y. De Wilde2, J. Decobert3, J.-L. Gentner3, A. Accard3, G.H. Duan3, and R. Colombelli1 Affiliations : Affiliations : 1Institut d’Electronique Fondamentale, Univ. Paris Sud and CNRS, UMR8622, 91405 Orsay, France 2 Institut Langevin, ESPCI ParisTech, CNRS, 10 rue Vauquelin, 75231 Paris Cedex 05, France 3 III-V Lab, Joint lab of 'Alcatel-Lucent Bell Labs France 'Thales Research and Technology' and 'CEA Leti‘ Route de Nozay, 91461 Marcoussis cedex, France Resume : Surface plasmon polaritons (SPPs) allow one to confine the electromagnetic field below the diffraction limit, opening interesting perspectives in chemical and biological detection, for instance. Nevertheless, SPPs experience very large ohmic losses because of their intrinsic nature of electromagnetic waves confined at a metal interface. In order to implement practical applications, ohmic losses need to be compensated, and integrated SPP generators could be of great use.
We propose to employ a semiconductor gain medium based on tensile strained semiconductor quantum wells which amplifies transverse magnetic (TM) light at telecom wavelengths (λ=1.3 μm). The high gain performance and polarization selectivity [1] make this active region (AR) suitable as a light source for SPP generation and amplification.
We fabricated lasers based on this semiconductor material, and we first studied the effect of the proximity of the top metal contact on the device performances. Interestingly, a device with metallic contacts very close to the active region – which we call thin cladding structure – is still capable of lasing action [2]. This result represents the basic building block to realize the coupling with a SPP propagating at the interface between air and the top metal contact, as designed in [3].
We then employed the same device architecture to explore the possibility of reducing the plasmonic ohmic losses via the sole patterning of the top metal layer. Initial results show that a laser threshold reduction can be observed if a metallic first order distributed feedback (DFB) grating is implemented. Furthermore, the DFB laser correctly operates on a single mode (spectral analysis and SNOM characterizations of the mode profile).
We believe that the integrated approach based on semiconductor active cores and electrical injection is promising for the development of SPP amplifiers. Furthermore, the fundamental study of the metal proximity to a gain media, combined with the electrical injection, opens the way to the development of electrically pumped semiconductor spasers and nanocavities.
[1] J. Decobert, N. Lagay, C. Cuisin, B. Dagens, B. Thedrez, and F. Laruelle, "MOVPE growth of AlGaInAs–InP highly tensile-strained MQWs for 1.3 mm low threshold lasers," Journal of Crystal Growth, vol. 272, pp. 543, 2004.
[2] D. Costantini, A. Bousseksou, M. Fevrier, B. Dagens, R. Colombelli, "Loss and gain measurements of tensile-strained quantum well diode lasers for plasmonic devices at telecom wavelengths", Journal of Quantum Electronics, 48, p73 (2012).
[3] J.-P. Tetienne, A. Bousseksou, D. Costantini, Y. De Wilde, and R. Colombelli, " Design of an integrated coupler for the electrical generation of surface plasmon polaritons", Opt Exp., vol. 19, no. 19, pp. 18155-18163, 2011 | 17 37 |
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